With higher versatility of mobile instruments and electronization of automobiles, “chip-type” compact coil components or inductance components have found a wide range of use. In particular, laminated inductance components (laminated inductors), which can be thinned, are recently being developed for power devices passing a large electric current.
To allow for a large electric current, it is attempted to replace a magnetic portion of a laminated inductor conventionally made of NiCuZn-based ferrite with that made of a FeCrSi alloy having a higher saturation magnetic flux density. However, a FeCrSi alloy has a lower volume resistivity than the conventionally used ferrite, and therefore, it is necessary to increase its volume resistivity.
To overcome this problem, Japanese Patent Application Publication No. 2010-62424 (the “424 Publication”) discloses a method of fabricating an electronic component including adding glass composed mainly of SiO2, B2O3, and ZnO into magnetic alloy powder including Fe, Cr, and Si, and firing the powder in a nonoxidizing atmosphere (700° C.). In this method, the insulation resistance of a fabricated product can be increased without increasing the resistance of a coil formed in the product.
However, in the method of '424 Publication, the volume resistivity of the magnetic portion is increased by the glass added into the magnetic alloy powder, and therefore, it is necessary to add a larger amount of glass in order to obtain a desired insulation resistance of the magnetic portion. As a result, the filling ratio of the magnetic alloy power is reduced, making it difficult to obtain high inductance characteristics. This problem is more significant as the inductor is thinner.
The magnetic alloy powder forming the magnetic portion has primarily been intended to have a high magnetic permeability and has been including particles having as large a diameter as possible, as long as such particles do not restrict other characteristics of the magnetic alloy powder. However, since large diameter particles tend to produce a large surface roughness, the thickness of a stacked layer was enlarged in accordance with the particle diameter. For example, the thickness of a stacked layer was varied so as to include six or more particles having a diameter of 10 μm or five or more particles having a diameter of 6 μm arranged in the stacking direction. This was in order to prevent reduction of magnetic permeability caused by the magnetic alloy powder having a small particle diameter, as described above.